1. Field of the Invention
The present invention relates to an X-ray radiograph apparatus which displays the number of remaining unused X-ray sheet films in the form of a bar graph.
2. Description of the Related Art
To improve the safety in X-ray radiograph, it is important to shorten the X-ray radiation period as well as to make the operation accurate.
According to conventional X-ray radiograph apparatuses, particularly, cassetteless X-ray radiograph apparatuses provided with a film feed magazine, it is necessary to inform an operator of the number of remaining unused sheet films retained in the magazine. Examples of such informing means are as follows.
The first means is to inform the operator of the number of remaining unused sheet films by displaying a "numeral." The displayed "numeral" becomes smaller by "1" every time one sheet film is used. If there are plural sizes of the magazines, i.e., plural sizes of the sheet films, plural numeral display sections are provided for each size.
The second means is to inform the operator by displaying a "bar graph." This "bar graph" display is made in such a way that multiple bars which can be lit and turned off are provided, each corresponding to a rough number of remaining unused sheet films, e.g., ten, these bars are turned off one by one every time ten sheet films are used.
According to the first conventional method which employs the "numeral" display to inform the operator of the number of remaining unused sheet films, it is difficult for the operator to quickly perceive the number of remaining unused sheet films. This is because the human perceives the volume based on a logarithmic manner. When there are different sizes of the sheet films, it becomes harder to quickly perceive the number of remaining unused sheet films by means of the numeral.
Further, since the number of the films initially set in the magazine are unknown or it is troublesome for the operator to count the initial number of the films set in the magazine, a conventional film detector detects the number of the unused films based on a total thickness of the remaining unused sheet films contained in the magazine and the thickness of one sheet film which is known. Therefore, if a slight amount of air is normally present between the sheet films, this affects the detector to detect the exact number of remaining films. If the total height of the air present between the sheet films is larger than the thickness of the film, the detector erroneously counts the number of the films. Thus, it is difficult to detect the accurate number of the films and is unnecessary to precisely display the number of the films if the number is large.
According to the second conventional method employing the "bar graph" display to inform the operator of the number of remaining unused sheet films, when the remaining number becomes smaller than the rough number indicated by the bar, the operator cannot know the accurate number of remaining unused sheet films.
The shortcomings of the conventional means for informing the operator of the number of remaining unused sheet films affect the radiograph operation as follows.
As it is difficult to perceive the proper timing for replacement of the film feed magazine in order to supplement sheet films, unused sheet films are likely to run out during a radiograph of a patient, thus requiring the supplement of unused sheet films during the radiation period of the X-ray. This inevitably makes the radiation period of the X-ray longer due to the supplementing action. This is critical to the human body particularly in the case a contrast medium is injected in the human under examination. In other words, when the supplement of unused sheet films is conducted after injection of a contrast medium, the contrast medium would flow out from the region of interest during this supplementing action, and additional contrast medium should be injected. Further, to check that the contrast medium has reached the region of interest, radiation of the X-ray should be performed again, thus increasing the amount of X-ray radiated to the human under examination.